Methods to make glass compositions and fibers made therefrom

ABSTRACT

Embodiments of the present invention provides fiberizable glass compositions formed from batch compositions comprising amounts of one or more glassy minerals, including perlite and/or pumice.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of currently pending U.S. patent application Ser. No. 13/365,590, filed Feb. 3, 2012, which is a continuation-in-part application of currently pending U.S. patent application Ser. No. 12/534,490, filed Aug. 3, 2009, which are each incorporated by reference as though fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to glass compositions and, in particular, to glass compositions for forming fibers.

BACKGROUND OF THE INVENTION

Large scale commercial production of continuous glass fibers (E-glass and C-glass types) comprises melting batch materials consisting primarily of minerals that are crystalline or substantially crystalline in nature. Conversion of these crystalline raw materials to a glassy state requires significant energy to be applied during the melting process. In view of the significant energy investment accompanying crystalline materials, glassy or amorphous minerals have sometimes been used in the production of glass compositions. A glassy or amorphous structure can reduce the amount of energy consumed in the melting process. Glassy minerals such as basalt and obsidian, for example, have been used as significant portions of feedstock for the production of mineral wool.

An associated disadvantage with some glassy minerals, however, is the high iron content of such minerals. Basalt and obsidian both comprise relatively large amounts of iron, thereby making their resulting melts highly energy absorbing. As a result, use of conventional gas fired furnaces is typically impractical for melt processing of these minerals. Electrical melting can be used to process glassy minerals of high iron content, but this is often a constraint in high volume glass fiber production as compared with conventional gas fired furnace technology. Raw materials used in the production of E-glass and C-glass fibers are generally low in iron, thereby permitting the use of large scale gas fired furnaces.

Perlite (and its expanded form pumice) is a mineral that naturally occurs in the glassy form. Perlite has not been extensively used as a raw material in glass production, partially because of its compositional parameters. The major constituents of perlite are SiO₂, Al₂O₃ and alkali oxide (R₂O). SiO₂ is typically present in perlite in an amount between about 70 and about 75 weight percent. Al₂O₃ is typically present in perlite in an amount between about 12 and about 15 weight percent. Alkali oxides are typically present in perlite in an amount between about 3 and about 9 weight percent. These parameters conflict with the compositional requirements of several widely used glass compositions, including, for example, those of E-glass and C-glass.

E-glass compositions, for example, are well-suited for forming glass fibers. As a result, the majority of glass fibers used in reinforcement applications, such as polymeric reinforcement applications, are formed from E-glass compositions. E-glass compositions generally limit the amount alkali oxides to no more than 2 percent. The high alkali oxide content of perlite is inconsistent with this limitation and renders perlite largely unsuitable for use in batch compositions for the production of E-glass compositions.

Moreover, C-glass compositions have also been used to form fibers resistant to corrosion in acidic environments. In order to resist acidic corrosion, C-glass compositions comprise a high SiO₂ content and a low Al₂O₃ content (<8 wt. %). The high Al₂O₃ content of perlite generally precludes use of perlite in batch compositions for the production of C-glass compositions.

SUMMARY

In one aspect, the present invention provides glass compositions formed from batch compositions comprising significant amounts of one or more glassy minerals, including perlite and/or pumice. In another aspect, the present invention provides glass fibers formed from glass compositions described herein.

In one embodiment, the present invention provides a glass composition formed from a batch composition comprising at least 10 weight percent of a glassy mineral, at least 5 weight percent of a sodium source, wherein the glassy mineral comprises a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some such embodiments, the batch composition comprises at least 25 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some further such embodiments, the batch composition comprises at least 40 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some embodiments, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ is perlite, pumice or mixtures thereof.

Moreover, in some embodiments, the batch comprises at least 10 weight percent of a sodium source. A sodium source, in some embodiments, comprises sodium carbonate (soda).

In some embodiments, the batch comprises at least 10 weight percent of a source of both silicon and aluminum. In some such embodiments, the source of both silicon and aluminum is an aluminum-containing silicate mineral, such kaolinite, dickite, halloysite, nacrite, montmorillonite, or alkali metal aluminosilicates. In some embodiments, the batch comprises at least 10 weight percent of a source of silicon. In some embodiments, the batch comprises at least 10 weight percent of a source of aluminum.

In another embodiment, the present invention provides a glass composition comprising 53-64 weight percent SiO₂, 8-12 weight percent Al₂O₃, 8.5-18 weight percent alkali oxide (R₂O) component and a metal oxide (RO) component, wherein the metal oxide component is present in an amount to provide a mass ratio of R₂O/RO ranging from about 0.15 to about 1.5. In some such embodiments, the glass composition includes 10-12 weight percent Al₂O₃.

In some embodiments, a R₂O component comprises Na₂O, K₂O or Li₂O or mixtures thereof. In some embodiments, a glass composition of the present invention comprises Na₂O in an amount ranging from 6.5 weight percent to about 16 weight percent. A glass composition, in some embodiments, comprises K₂O in an amount ranging from 0.5 weight percent to 4 weight percent, and 2 weight percent to 4 weight percent in further embodiments. In some embodiments, a glass composition comprises Li₂O in an amount up to 2 weight percent.

In some embodiments, a RO component comprises MgO, CaO, SrO, BaO, or ZnO or mixtures thereof. A RO component, in some embodiments, is present in a glass composition of the present invention in an amount ranging from 7 weight percent to 31 weight percent. In one embodiment, a glass composition comprises MgO in an amount up to about 5 weight percent. A glass composition, in some embodiments, comprises CaO in an amount ranging from 7 weight percent to 26 weight percent. In some embodiments, a glass composition comprises ZnO in an amount up to 3 weight percent.

Glass compositions of the present invention, in some embodiments, comprise metal oxides in addition to RO including, but not limited to, ZrO₂, TiO₂, MnO₂ or La₂O₃ or mixtures thereof.

In another embodiment, the present invention provides a glass composition comprising 56-63 weight percent SiO₂, 9-12 weight percent Al₂O₃, 12-17 weight percent RO (CaO+MgO), 12-14 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass composition comprising 60-64 weight percent SiO₂, 9-12 weight percent Al₂O₃, 7-15 weight percent RO (CaO+MgO), 13-15.5 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass composition comprising 55-63 weight percent SiO₂, 9-14 weight percent Al₂O₃, 11-16.5 weight percent RO (CaO+MgO), 14-17 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In some embodiments, glass compositions of the present invention have an Fe₂O₃ content of less than 1 weight percent. Glass compositions, in other embodiments, can comprise less than 0.7 weight percent Fe₂O₃.

Glass compositions, according to some embodiments of the present invention are fiberizable. In some embodiments, glass compositions of the present invention have a forming temperature (T_(F)) ranging from 1120° C. to about 1300° C. As used herein, the term “forming temperature” means the temperature at which the glass composition has a viscosity of 1000 poise (or “log 3 temperature”). In some embodiments, glass compositions of the present invention are fiberizable at the forming temperature.

Moreover, in some embodiments, glass compositions of the present invention have a liquidus temperature (T_(L)) ranging from about 1020° C. to about 1240° C. In some embodiments, the difference between the forming temperature and the liquidus temperature of a glass composition of the present invention ranges from about 45° C. to about 165° C. In some embodiments, the difference between the forming temperature and the liquidus temperature of a glass composition of the present invention is at least 65° C.

In some embodiments, glass compositions of the present invention have a molten density at the forming temperature ranging from 2.35 g/cm³ to 2.40 g/cm³. In some embodiments, glass composition of the present invention have molten density ranging from 2.36 g/cm³ to 2.38 g/cm³.

Glass compositions of the present invention, in some embodiments, have a molten surface tension at the forming temperature ranging from about 390 E⁻³ N/m to 400 E⁻³ N/m.

As provided herein, glass fibers can be formed from some embodiments of the glass compositions of the present invention. In some embodiments, fibers formed from glass compositions of the present invention have a modulus (E) ranging from about 53 GPa to about 65 GPa. Moreover, in some embodiments, fibers formed from glass compositions of the present invention have a specific strength ranging from 1.30-1.35 E⁵ m.

Fibers formed from glass compositions of the present invention, in some embodiments, also demonstrate acidic and alkaline corrosion resistance. In one embodiment, for example, a fiber formed from a glass composition of the present invention has a weight loss (wt. %) ranging from about 0.55 to about 0.60 when exposed to 1N H₂SO₄ (pH 0) at 100° C. for one hour. In another embodiment, a fiber formed from a glass composition of the present invention has a weight loss (wt. %) ranging from about 0.25 to 0.30 when exposed to 0.1N NaOH (pH 12) at 100° C. for one hour.

Glass fibers formed from glass compositions of the present invention can be used in various reinforcement applications. In some embodiments, glass fibers of the present invention are used in the reinforcement of polymers including thermoplastics and thermosets. In some embodiments, glass fibers formed from glass compositions of the present invention are used in the reinforcement of building materials including, but not limited to, cement and roofing systems such as shingles.

In another aspect, the present invention provides methods of making glass compositions from batch compositions comprising significant amounts of one or more glassy minerals, including perlite and/or pumice.

In one embodiment, a method of making a glass composition of the present invention comprises providing a batch composition comprising at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent and heating the batch composition to a temperature sufficient to form the glass composition. In some embodiments, the batch comprises at least 10 weight percent of an additional source of both silicon and aluminum. In some embodiments, the batch comprises at least 10 weight percent of an additional source of silicon. In some embodiments, the batch comprises at least 10 weight percent of an additional source of aluminum. In some embodiments, the batch composition is heated to a temperature of about 1400° C. to about 1450° C.

These and other embodiments are presented in greater detail in the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides the results of a high temperature differential thermal analysis (DTA) comparing conversion from solid to liquid of fine particulate perlite and a coarse particulate perlite according to one embodiment of the present invention.

FIG. 2 illustrates an apparatus used in the determination of melt viscosities of glass compositions according to embodiments of the present invention.

FIG. 3 illustrates the position of the thermocouple and the number of turns of the heating coil of a furnace used in the determination of liquidus temperatures (T_(L)) of glass compositions according to embodiments of the present invention.

FIG. 4 provides temperature-viscosity curves for a glass composition according to one embodiment of the present invention, two commercially available E-glass compositions and a C-glass composition.

FIG. 5 provides molten glass surface tensions as a function of temperature for a glass composition according to one embodiment of the present invention and two commercially available E-glass compositions.

FIG. 6 is a plot of the melt or molten glass density as a function of temperature for a glass composition according to one embodiment of the present invention and two commercially available E-glass compositions.

FIG. 7 is a plot electrical of conductivity as a function of temperature for a glass composition according to one embodiment of the present invention as well as E-glass and C-glass compositions.

FIG. 8 provides energy requirements for conversion of several batch compositions to glass melt compositions according to one embodiment of the present invention.

FIG. 9 summarizes Weibull statistical analysis of fiber strengths of various glass compositions according to some embodiments of the present invention.

DETAILED DESCRIPTION

Unless indicated to the contrary, the numerical parameters set forth in the following specification are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10. Additionally, any reference referred to as being “incorporated herein” is to be understood as being incorporated in its entirety.

It is further noted that, as used in this specification, the singular forms “a,” “an,” and “the” include plural referents unless expressly and unequivocally limited to one referent.

Certain embodiments of the present invention can employ the various thermodynamic and processing advantages offered by glassy minerals to provide glass compositions having desirable properties. In one aspect, the present invention provides glass compositions formed from batch compositions comprising significant amounts of one or more glassy minerals, including perlite and/or pumice. The glass compositions, in some embodiments, can be fiberizable glass compositions. In some embodiments, glass fibers formed from glass compositions of the present invention can demonstrate advantageous properties including, but not limited to, mechanical and corrosion resistant properties equaling or exceeding glass fibers formed from previous compositions, such as E-glass and C-glass compositions.

Various embodiments of the present invention provide glass compositions, including, without limitation, fiberizable glass compositions. In one embodiment, the present invention provides a glass composition formed from a batch composition comprising at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, wherein the glassy mineral comprises a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some embodiments, the batch composition comprises at least 25 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In another embodiment, the batch composition comprises at least 40 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent.

In some embodiments, a glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent is perlite, pumice or mixtures thereof.

Moreover, in some embodiments, the batch composition comprises at least 10 weight percent of a sodium source. In another embodiment, the batch composition comprises at least 12 weight percent of a sodium source. A suitable sodium source for use in batch compositions of the present invention, in some embodiments, comprises sodium carbonate (soda).

In some embodiments, the batch comprises at least 10 weight percent of an additional source of both silicon and aluminum. In some such embodiments, the source of both silicon and aluminum is an aluminum-containing silicate mineral, such kaolinite, dickite, halloysite, nacrite, montmorillonite, or alkali metal aluminosilicates. In some embodiments, the batch comprises at least 10 weight percent of an additional source of silicon. In some such embodiments, the source of silicon can be a silicon-containing mineral, such as silica. In some embodiments, the batch comprises at least 10 weight percent of an additional source of aluminum. In such embodiments, the source of aluminum can be an aluminum-containing mineral, such as corundum.

In another embodiment, the present invention provides a glass composition comprising 53-64 weight percent SiO₂, 8-12 weight percent Al₂O₃, 8.5-18 weight percent alkali oxide (R₂O) component and a metal oxide (RO) component, wherein the metal oxide component is present in an amount to provide a mass ratio of R₂O/RO ranging from about 0.15 to about 1.5.

In some embodiments, a R₂O component is not limited to a single compound but can comprise several compounds. In some embodiments, a R₂O component comprises Na₂O, K₂O or Li₂O or mixtures thereof. Moreover, in some embodiments and without limitation, a R₂O component can mean Na₂O only, K₂O only, Li₂O only, a combination of Na₂O and K₂O, a combination of K₂O and Li₂O, a combination of Na₂O and Li₂O, or a combination of Na₂O, K₂O and Li₂O.

In some embodiments, a glass composition of the present invention comprises Na₂O in an amount ranging from 6.5 weight percent to about 16 weight percent. In another embodiment, a glass composition comprises Na₂O in an amount ranging from 9 weight percent to 13 weight percent. In some embodiments, a glass composition comprises Na₂O in an amount ranging from 10 weight percent to 12.5 weight percent.

In some embodiments, a glass composition of the present invention comprises K₂O in an amount ranging from 0.5 weight percent to 4 weight percent. A glass composition of the present invention, in some embodiments, comprises K₂O in an amount ranging from 2 weight percent to 4 weight percent. In some embodiments, a glass composition comprises K₂O in an amount ranging from 2.5 weight percent to 3.5 weight percent.

In some embodiments, a glass composition of the present invention comprises Li₂O in an amount up to 2 weight percent. A glass composition, in another embodiment, comprises Li₂O in an amount ranging from 0.5 weight percent to 1.5 weight percent.

In some embodiments, a RO component comprises MgO, CaO, SrO, BaO or ZnO or mixtures thereof In some embodiments, a RO component can comprise MgO only, CaO only, SrO only, BaO only or ZnO only. In some embodiments, a RO component can comprise any combination of two or more metal oxides of MgO, CaO, SrO, BaO and ZnO. A RO component, in some embodiments, is present in a glass composition of the present invention in an amount ranging from 7 weight percent to 31 weight percent.

In one embodiment, a glass composition of the present invention comprises MgO in an amount up to 5 weight percent. A glass composition, in another embodiment, comprises MgO in an amount ranging from 1 weight percent to 4 weight percent. In some embodiments, a glass composition comprises MgO in an amount ranging from 2 weight percent to 3 weight percent.

In some embodiments, a glass composition of the present invention comprises CaO in an amount ranging from 7 weight percent to 26 weight percent. A glass composition, in another embodiment, comprises CaO in an amount ranging from 8 weight percent to 20 weight percent. In some embodiments, a glass composition comprises CaO in an amount ranging from 10 weight percent to 14 weight percent.

In some embodiments, a glass composition comprises ZnO in an amount up to 3 weight percent.

Glass compositions of the present invention, in some embodiments, comprise metal oxides in addition to RO including, but not limited to ZrO₂, TiO₂, MnO₂ or La₂O₃ or mixtures thereof. In some embodiments, a glass composition can comprise ZrO₂ in an amount up to 3 weight percent, TiO₂ in an amount up to 3 weight percent, MnO₂ in an amount up to 3 weight percent and/or La₂O₃ in an amount up to 3 weight percent.

In another embodiment, the present invention provides a glass composition comprising 56-63 weight percent SiO₂, 9-12 weight percent Al₂O₃, 12-17 weight percent RO (CaO+MgO), 12-14 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass composition comprising 60-64 weight percent SiO₂, 9-12 weight percent Al₂O₃, 7-15 weight percent RO (CaO+MgO), 13-15.5 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass composition comprising 55-63 weight percent SiO₂, 9-14 weight percent Al₂O₃, 11-16.5 weight percent RO (CaO+MgO), 14-17 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃. In some embodiments, glass compositions of the present invention have an Fe₂O₃ content of less than 1 weight percent. Glass compositions, in other embodiments, can comprise less than 0.7 weight percent Fe₂O₃.

Glass compositions of the present invention, in some embodiments, have a forming temperature (T_(F)) ranging from about 1120° C. to about 1300° C. In another embodiment, glass compositions of the present invention have a forming temperature ranging from about 1150° C. to about 1250° C. In some embodiments, glass compositions have a forming temperature ranging from about 1200° C. to about 1225° C.

Glass compositions of the present invention, in some embodiments, have a liquidus temperature ranging from about 1020° C. to about 1240° C. In another embodiment, glass compositions of the present invention have a liquidus temperature ranging from about 1070° C. to about 1200° C. In some embodiments, glass compositions of the present invention have a liquidus temperature ranging from about 1110° C. to about 1140° C.

In some embodiments, the difference between the forming temperature and the liquidus temperature of a glass composition of the present invention ranges from about 45° C. to about 165° C. In some embodiments, the difference between the forming temperature and the liquidus temperature of a glass composition of the present invention is at least 65° C.

In some embodiments, glass compositions of the present invention have a molten density at the forming temperature ranging from 2.35 g/cm³ to 2.40 g/cm³. In some embodiments, glass compositions of the present invention have molten density ranging from 2.36 g/cm³ to 2.38 g/cm³. As discussed further herein, in some embodiments, molten densities of some glass compositions of the present invention are 5% to 7% lower than the molten densities of some E-glass compositions. As a result, glass fibers formed from some glass compositions of the present invention are lighter per unit volume in comparison to some E-glass fibers. Lighter glass fibers can be advantageous in many applications, particularly material reinforcement applications, such as polymeric reinforcement applications, where weight savings are often highly desirable. Moreover, as a result of lower densities, glass fibers formed from some glass compositions of the present invention can have larger diameters in comparison to some E-glass fibers of the same weight, thereby providing enhanced mechanical properties.

Additionally, glass compositions of the present invention, in some embodiments, have a molten surface tension at the forming temperature ranging from about 390 E⁻³ N/m to 400 E⁻³ N/m.

As provided herein, glass compositions of the present invention can be produced from batch compositions comprising a significant amount of one or more glassy minerals, including perlite and/or pumice. In being produced from batch compositions comprising a significant amount of glassy minerals, glass compositions of the present invention can realize sizable energy savings in some embodiments. As discussed further herein, in some embodiments, production of a melt of a glass composition of the present invention requires up to 33% less energy in comparison to that required to produce a melt of some E-glass compositions.

Glass compositions of the present invention can be produced by several methods. In one embodiment, a method of producing a glass composition comprises providing a batch composition comprising at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent and heating the batch composition to a temperature sufficient to form a melt of the glass composition. In some embodiments, the batch composition is heated to a temperature of about 1400° C. to about 1450° C. In some embodiments, the batch comprises at least 10 weight percent of an additional source of both silicon and aluminum. In some such embodiments, the source of both silicon and aluminum is an aluminum-containing silicate mineral, such kaolinite, dickite, halloysite, nacrite, montmorillonite, or alkali metal aluminosilicates. In some embodiments, the batch comprises at least 10 weight percent of an additional source of silicon. In some embodiments, the batch comprises at least 10 weight percent of an additional source of aluminum.

In some embodiments, the batch composition comprises at least 25 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In another embodiment, the batch composition comprises at least 40 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent.

In some embodiments, a glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent is perlite, pumice or mixtures thereof. Perlite and/or pumice used in the production of glass compositions of the present invention, in some embodiments, is provided in particulate or powder form. In some embodiments, additional energy savings can be realized by using perlite and/or pumice compositions having fine particle size as opposed to coarser particle sizes. FIG. 1 illustrates the results of a high temperature differential thermal analysis (DTA) comparing the conversion from solid to liquid of a fine particulate perlite (about 200 mesh) and a coarse particulate perlite (about 45 mesh). As illustrated in FIG. 1, the fine particulate perlite requires less energy during conversion from solid to liquid in comparison to the coarse particulate perlite, although both the fine and the coarse particulate perlite are glassy or amorphous at room temperature. Moreover, the fine particulate perlite begins liquid formation at a lower temperature than the coarse particulate perlite.

Moreover, in some embodiments, batch compositions of the present invention comprise at least 10 weight percent of a sodium source. In some embodiments, batch compositions comprise at least 12 weight percent of a sodium source. A suitable sodium source for use in batch compositions of the present invention, in some embodiments, comprises sodium carbonate (soda).

In some embodiments, batch compositions used to produce glass compositions of the present invention further comprise other minerals including, but not limited to, limestone, dolomite or mixtures thereof. In one embodiment, for example, a batch composition further comprises up to 17 weight percent limestone. In another embodiment, a batch composition further comprises up to 13 weight percent dolomite.

As provided herein, glass fibers can be formed from any of the glass compositions of the present invention. Glass fibers according to the various embodiments of the present invention can be formed using any process known in the art for forming glass fibers, and more desirably, any process known in the art for forming essentially continuous glass fibers. For example, although not limiting herein, the glass fibers according to non-limiting embodiments of the present invention can be formed using direct-melt or indirect-melt fiber forming methods. These methods are well known in the art and further discussion thereof is not believed to be necessary in view of the present disclosure. See, e.g., K. L. Loewenstein, The Manufacturing Technology of Continuous Glass Fibers, 3^(rd) Ed., Elsevier, N.Y., 1993 at pages 47-48 and 117-234.

In one embodiment, the present invention provides a glass fiber comprising a glass composition formed from a batch composition comprising at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, wherein the glassy mineral comprises a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some embodiments, the batch composition comprises at least 25 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In another embodiment, the batch composition comprises at least 40 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some embodiments, the batch composition comprises at least 10 weight percent of a source of both silicon and aluminum. In some embodiments, the batch comprises at least 10 weight percent of a source of silicon. In some embodiments, the batch comprises at least 10 weight percent of a source of aluminum.

In another embodiment, the present invention provides a glass fiber comprising 53-64 weight percent SiO₂, 8-12 weight percent Al₂O₃, 8.5-18 weight percent alkali oxide (R₂O) component and a metal oxide (RO) component, wherein the metal oxide component is present in an amount to provide a mass ratio of R₂O/RO ranging from about 0.15 to about 1.5. In some such embodiments, the glass composition includes 10-12 weight percent Al₂O₃.

In another embodiment, the present invention provides a glass fiber comprising 56-63 weight percent SiO₂, 9-12 weight percent Al₂O₃, 12-17 weight percent RO (CaO+MgO), 12-14 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass fiber comprising 60-64 weight percent SiO₂, 9-12 weight percent Al₂O₃, 7-15 weight percent RO (CaO+MgO), 13-15.5 weight percent R₂O (Na₂O+K₂O)), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a glass fiber comprising 55-63 weight percent SiO₂, 9-14 weight percent Al₂O₃, 11-16.5 weight percent RO (CaO+MgO), 14-17 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In some embodiments, fibers formed from glass compositions of the present invention have a modulus (E) ranging from about 53.0 GPa to about 65.0 GPa. In another embodiment, fibers formed form glass compositions of the present invention have a modulus (E) ranging from about 56 GPa to about 62 GPa. Moreover, in some embodiments, fibers formed from glass compositions of the present invention have a specific strength ranging from 1.30-1.35 E⁵ m.

Fibers formed from glass compositions of the present invention, in some embodiments, also demonstrate acidic and alkaline corrosion resistance. In one embodiment, for example, a glass fiber formed from a glass composition of the present invention has a weight loss (wt. %) ranging from 0.55 to 0.60 when exposed to 1N H₂SO₄ (pH 0) at 100° C. for one hour. In another embodiment, a glass fiber formed from a glass composition of the present invention has a weight loss (wt. %) ranging from 0.60 to 1.70 when exposed to 1N H₂SO₄ (pH 0) at 100° C. for one hour.

In another embodiment, a fiber formed from a glass composition of the present invention has a weight loss (wt. %) ranging from about 0.25 to about 0.30 when exposed to 0.1N NaOH (pH 12) at 100° C. for one hour. A fiber formed from a glass composition of the present invention, in some embodiments, has a weight loss (wt. %) ranging from 0.35 to 0.85 when exposed to 0.1N NaOH (pH 12) at 100° C. for one hour.

Although not limiting herein, glass fibers according to some embodiments of the present invention can be useful in structural reinforcement applications. In some embodiments, glass fibers of the present invention are used in the reinforcement of polymers including thermoplastics and thermosets. In some embodiments, glass fibers formed from glass compositions of the present invention are used in the reinforcement of building materials including, but not limited to, cement and roofing systems such as shingles.

In one embodiment, the present invention provides a polymeric composite comprising a polymeric material and at least one glass fiber in the polymeric material, the at least one glass fiber comprising a glass composition a formed from a batch composition comprising at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, wherein the glassy mineral comprises a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In some embodiments, the batch composition comprises at least 25 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent. In another embodiment, the batch composition comprises at least 40 weight percent of a glassy mineral, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent.

In another embodiment, the present invention provides a polymeric composite comprising a polymeric material and at least one glass fiber in the polymeric material, the at least one glass fiber comprising 53-64 weight percent SiO₂, 8-12 weight percent Al₂O₃, 8.5-18 weight percent alkali oxide (R₂O) component and a metal oxide (RO) component, wherein the metal oxide component is present in an amount to provide a mass ratio of R₂O/RO ranging from about 0.15 to about 1.5. In some such embodiments, the glass composition includes 10-12 weight percent Al₂O₃.

In another embodiment, the present invention provides a polymeric composite comprising a polymeric material and at least one glass fiber in the polymeric material, the at least one glass fiber comprising 56-63 weight percent SiO₂, 9-12 weight percent Al₂O₃, 12-17 weight percent RO (CaO+MgO), 12-14 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a polymeric composite comprising a polymeric material and at least one glass fiber in the polymeric material, the at least one glass fiber comprising 60-64 weight percent SiO₂, 9-12 weight percent Al₂O₃, 7-15 weight percent RO (CaO+MgO), 13-15.5 weight percent R₂O (Na₂O+K₂O)), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

In another embodiment, the present invention provides a polymeric composite comprising a polymeric material and at least one glass fiber in the polymeric material, the at least one glass fiber comprising 55-63 weight percent SiO₂, 9-14 weight percent Al₂O₃, 11-16.5 weight percent RO (CaO+MgO), 14-17 weight percent R₂O (Na₂O+K₂O), 0-2 weight percent Li₂O, 0-3 weight percent ZnO, 0-3 weight percent ZrO₂, 0-3 weight percent MnO₂ and 0-3 weight percent La₂O₃.

Polymeric composites according to the various embodiments of the present invention can be made by any method known in the art for making polymeric composites. For example, in one embodiment, polymeric composites according to the present invention can be made by impregnating woven fabrics or non-woven fabrics or mats of glass fibers with a polymeric material and then curing the polymeric material. In another embodiment, continuous glass fibers and/or chopped glass fibers comprising glass compositions of the present invention can be disposed in the polymeric material. Depending on the identity of the polymeric material, the polymeric material can be cured subsequent to receiving the continuous or chopped glass fibers.

Various non-limiting embodiments of the present invention will now be illustrated in the following, non-limiting examples.

Examples 1 through 6 of glass compositions of the present invention provided in Table I were prepared by providing mixtures of ingredients covering 65-72 weight percent perlite, 0-22 weight percent dolomite, 6-35 weight percent limestone and 0-8 weight percent soda. The specific amounts of perlite, dolomite, limestone and/or soda used to produce Examples 1 through 6 were determined by reference to the compositional parameters of each mineral in relation to the desired compositional parameters of each glass composition. Mixtures of the minerals were subsequently heated to a temperature of about 1400° C. to obtain molten glass compositions. The molten glass compositions were cooled to provide glass compositions of Examples 1 through 6.

TABLE I Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Fe₂O₃ TiO₂ SO₃ F M_(x)O_(y) 1 59.29 10.84 20.37 3.00 2.82 3.06 5.88 0.48 0.14 0.00 0.00 0.00 2 59.29 10.84 19.37 4.00 2.82 3.06 5.88 0.48 0.14 0.00 0.00 0.00 3 59.29 10.84 18.87 4.50 2.82 3.06 5.88 0.48 0.14 0.00 0.00 0.00 4 59.29 10.84 18.37 5.00 2.82 3.06 5.88 0.48 0.14 0.00 0.00 0.00 5 54.41 9.95 25.68 4.00 2.76 2.59 5.38 0.47 0.14 0.00 0.00 0.00 6 59.29 10.84 23.37 0.00 2.82 3.06 5.88 0.48 0.14 0.00 0.00 0.00

Examples 7 through 13 of glass compositions of the present invention provided in Table II were prepared by providing mixtures of ingredients covering 69-71 weight percent perlite, 6-20 weight percent limestone and 7-10 weight percent soda. The specific amounts of perlite, limestone and soda used to produce Examples 7 through 13 were determined by reference to the compositional parameters of each mineral in relation to the desired compositional parameters of each glass composition. Mixtures of the minerals were subsequently heated to a temperature of about 1400° C. to obtain molten glass compositions. The molten glass compositions were cooled to provide glass compositions of Examples 7 through 13.

TABLE II Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Fe₂O₃ TiO₂ SO₃ F M_(x)O_(y) 7 62.66 11.46 9.28 2.98 9.20 3.23 12.43 0.51 0.14 0.25 0.30 0.00 8 61.11 11.17 14.03 0.00 9.29 3.15 12.42 0.49 0.14 0.32 0.30 0.00 9 62.61 11.45 11.26 0.00 10.19 3.23 13.42 0.51 0.14 0.32 0.30 0.00 10 61.13 11.17 13.04 0.00 10.19 3.23 13.42 0.49 0.14 0.32 0.30 0.00 11 58.93 10.76 12.57 0.00 10.34 2.60 13.22 0.47 3.00 0.09 0.28 0.95* 12 58.93 10.76 12.57 0.00 10.34 2.60 13.22 0.47 1.08 0.09 0.28 2.87* 13 57.47 10.78 9.12 0.00 10.44 3.05 13.49 0.62 0.15 0.09 0.28 8.00* *ZrO₂ and TiO₂ were added to the batch composition used to produce the glass composition.

Examples 14 through 19 of glass compositions of the present invention provided in Table III were prepared by providing mixtures of ingredients covering 69-72 weight percent perlite, 0-13 weight percent dolomite, 3-17 weight percent limestone and 7-10 weight percent soda. The specific amounts of perlite, limestone, soda and/or dolomite used to produce Examples 14 through 19 were determined by reference to the compositional parameters of each mineral in relation to the desired compositional parameters of each glass composition. Mixtures of the minerals were subsequently heated to a temperature of about 1400° C. to obtain molten glass compositions. The molten glass compositions were cooled to provide glass compositions of Examples 14 through 19.

TABLE III Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Fe₂O₃ TiO₂ SO₃ F M_(x)O_(y) 14 62.62 11.45 10.77 0.00 10.69 3.23 13.92 0.51 0.14 0.30 0.30 0.00 15 61.91 11.38 7.99 3.00 11.21 3.27 14.48^(#) 0.60 0.14 0.20 0.00 1.0^(#)/0.30* 16 63.65 11.93 4.39 2.56 13.04 3.37 16.41 0.70 0.17 0.20 0.00 0.00 17 61.14 11.17 12.05 0.00 11.26 3.15 14.41 0.49 0.14 0.30 0.30 0.00 18 61.65 11.29 10.94 0.00 11.73 3.18 14.92 0.52 0.14 0.25 0.30 0.00 19 61.65 11.29 7.96 2.98 11.73 3.18 14.92 0.52 0.14 0.30 0.25 0.00 ^(#)1 wt % Li₂O replaced 1 wt % Na₂O; Sb₂O₃ used in refining removed *Sb₂O₃ used for refining

Examples 20 through 37 of glass compositions of the invention provided in Table IV were prepared by providing mixtures of ingredients covering 68-73 weight percent perlite, 0-13 weight percent dolomite, 4-16 weight percent limestone and 12-17 weight percent soda. The specific amounts of perlite, limestone, soda and/or dolomite used to produce Examples 20 through 37 were determined by reference to the compositional parameters of each mineral in relation to the desired compositional parameters of each glass composition. Mixtures of the minerals were subsequently heated to a temperature of about 1400° C. to obtain molten glass compositions. The molten glass compositions were cooled to provide glass compositions of Examples 20 through 37.

TABLE IV Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Fe₂O₃ TiO₂ SO₃ F M_(x)O_(y) 20 61.14 11.17 11.05 0.00 12.26 3.15 15.41 0.49 0.14 0.30 0.30 0.00 21 60.78 11.10 11.65 0.00 12.31 3.13 15.44 0.50 0.14 0.20 0.20 0.00 22 60.74 11.09 8.65 2.99 12.31 3.13 15.44 0.50 0.14 0.20 0.25 0.00 23 61.01 10.77 8.25 2.97 12.30 3.91 16.20 0.58 0.07 0.02 0.12 0.00 24 60.64 10.71 8.80 2.96 12.22 3.88 16.10 0.58 0.07 0.02 0.12 0.00 25 60.94 10.76 8.79 2.54 12.28 3.90 16.18 0.58 0.07 0.02 0.12 0.00 26 60.22 10.63 9.15 2.52 10.54 3.86 14.40 2.88 0.07 0.02 0.11 0.00 27 60.92 10.76 8.24 2.97 12.28 3.90 16.18 0.58 0.07 0.18 0.12 0.00 28 60.55 10.69 8.78 2.96 12.20 3.88 16.08 0.58 0.07 0.18 0.12 0.00 29 60.84 10.74 8.77 2.54 12.26 3.90 16.15 0.58 0.07 0.18 0.12 0.00 30 60.12 10.62 9.13 2.51 10.53 3.85 14.38 2.88 0.07 0.17 0.11 0.00 31 55.33 9.77 12.86 5.38 4.59 3.54 8.13 0.54 0.06 0.07 0.11 7.75* 32 58.03 10.25 13.49 5.64 4.81 3.71 8.53 0.56 0.07 0.07 0.11 3.25* 33 55.59 9.82 6.17 3.06 10.03 3.56 13.59 0.53 0.06 0.07 0.11 11.01** 34 62.34 14.32 11.20 0.38 9.04 2.17 11.21 0.34 0.04 0.11 0.06 0.00 35 62.87 11.50 7.98 0.00 13.25 3.24 16.50 0.51 0.14 0.30 0.20 0.00 36 61.14 11.17 10.06 0.00 13.25 3.15 16.40 0.49 0.14 0.30 0.30 0.00 37 60.25 11.01 9.00 1.98 12.70 3.54 16.24 0.81 0.03 0.12 0.00 0.00 *B₂O₃ used as additives **ZnO used to replace 1 wt % Na₂O and 1 wt % CaO plus Sb₂O₃ removal

The glass composition of Example 38 provided in Table V was prepared in accordance with the glass composition of Example 12 above, except 1 wt % Li₂O was used to replace 1 wt % Na₂O and any Sb₂O₃ used during refining was removed. The glass composition of Example 39 in Table V was prepared in accordance with the glass composition of Example 12 above, except ZnO was used to replace 1 wt % Na₂O and 1 wt % CaO and any Sb₂O₃ used during refining was removed.

TABLE V Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Fe₂O₃ TiO₂ SO₃ F M_(x)O_(y) 38 61.93 11.34 7.99 3.00 10.29 3.20 13.49 0.52 0.14 0.30 0.30 1.00 39 61.93 11.34 6.99 3.00 10.29 3.20 13.49 0.52 0.14 0.30 0.30 2.00

Examples 40 through 71 of glass compositions of the present invention provided in Table VI were prepared in accordance with the glass composition of Example 12 above, except the glass compositions were designed to include various combinations of Li₂O, La₂O₃, MnO₂, TiO₂, ZnO and ZrO₂. Various amounts of Li₂CO₃, La₂O₃, MnO₂, TiO₂, ZnO and ZrO₂ were incorporated into the batch composition of Example 12 to produce Examples 39-70. Moreover, each of the glass compositions of Examples 39-70 also included 0.09 wt % SO₃, 0.27-0.28 wt % F and 0.53-0.55 wt % Fe₂O₃.

TABLE VI Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O R₂O Li₂O ZnO ZrO₂ TiO₂ La₂O₃ MnO₂ 40 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 0.91 2.74 0.91 2.74 41 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 2.74 0.91 2.74 0.91 0.91 42 57.22 10.52 7.38 2.77 10.33 3.01 13.34 1.38 0.92 2.77 0.92 0.92 0.92 43 54.70 10.06 7.06 2.65 9.87 2.87 12.75 0.44 2.65 0.88 2.65 2.65 2.65 44 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 0.89 0.89 2.67 2.67 45 53.29 9.80 6.88 2.58 9.62 2.80 12.42 1.29 2.58 2.58 2.58 2.58 2.58 46 54.70 10.06 7.06 2.65 9.87 2.87 12.75 0.44 2.65 2.65 2.65 0.88 2.65 47 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 0.89 2.67 2.67 0.89 2.67 48 58.85 10.82 7.59 2.85 10.62 3.09 13.72 0.47 0.95 0.95 0.95 0.95 0.95 49 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 2.74 0.91 2.74 0.91 50 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 2.74 0.91 0.91 2.74 0.91 51 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 0.89 2.67 2.67 0.89 52 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 2.67 0.89 2.67 0.89 53 54.70 10.06 7.06 2.65 9.87 2.87 12.75 0.44 2.65 2.65 0.88 2.65 2.65 54 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 0.91 2.74 2.74 0.91 55 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 0.89 0.89 2.67 2.67 2.67 56 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 0.89 2.67 2.67 2.67 0.89 57 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 2.74 0.91 0.91 2.74 58 57.22 10.52 7.38 2.77 10.33 3.01 13.34 1.38 2.77 0.92 0.92 0.92 0.92 59 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 0.89 2.67 0.89 2.67 60 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 0.91 0.91 2.74 2.74 61 57.22 10.52 7.38 2.77 10.33 3.01 13.34 1.38 0.92 0.92 2.77 0.92 0.92 62 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 2.67 2.67 0.89 0.89 63 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 2.74 2.74 0.91 0.91 0.91 64 54.70 10.06 7.06 2.65 9.87 2.87 12.75 0.44 0.88 2.65 2.65 2.65 2.65 65 57.22 10.52 7.38 2.77 10.33 3.01 13.34 1.38 0.92 0.92 0.92 0.92 2.77 66 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 0.89 2.67 0.89 2.67 2.67 67 54.70 10.06 7.06 2.65 9.87 2.87 12.75 0.44 2.65 2.65 2.65 2.65 0.88 68 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 2.74 0.91 0.91 0.91 2.74 69 55.18 10.15 7.12 2.67 9.96 2.90 12.86 1.34 2.67 2.67 0.89 0.89 2.67 70 57.22 10.52 7.38 2.77 10.33 3.01 13.34 1.38 0.92 0.92 0.92 2.77 0.92 71 56.70 10.43 7.32 2.74 10.23 2.98 13.21 0.46 0.91 2.74 2.74 0.91 0.91

Examples 72 through 74 of glass compositions of the present invention provided in Table VII may be prepared by providing mixtures of ingredients covering 11-41 weight percent perlite, 0-55 weight percent dolomite, 12-17 weight percent limestone, 0-30 weight percent alkali aluminosilicate mineral, 34-56 weight percent silica, 0-19 weight percent clay (kaolinite), and 1-3 weight percent rouge. The specific amounts of perlite, dolomite, alkali aluminosilicate mineral, silica, clay and/or rouge used to produce Examples 72 through 74 were determined by reference to the compositional parameters of each mineral in relation to the desired compositional parameters of each glass composition. Mixtures of the minerals are heated to a temperature of about 1400° C. to obtain molten glass compositions. The molten glass compositions are cooled to provide glass compositions of Examples 72 through 74.

TABLE VII Glass Compositions Ex. SiO₂ Al₂O₃ CaO MgO Na₂O K₂O TiO₂ Fe₂O₃ 72 61.60 10.64 11.27 0.56 13.10 2.38 0.01 0.44 73 61.56 10.68 11.08 0.59 13.58 2.08 0.02 0.42 74 62.44 10.70 10.51 1.76 12.91 0.70 0.37 0.61

I. Melt Properties

The melt properties of several glass compositions of Examples 1 through 71 were investigated. Investigation of the melt properties of glass compositions of the present invention assisted in the determination of how various compositional parameters affect processing considerations including forming temperatures (T_(F)) and liquidus (T_(L)) temperatures of the glass compositions.

The measurement of melt viscosity for determining forming temperatures of various glass compositions of the present invention was done by the counter-balance method over the viscosity range of 10²-10⁵ Poise. The apparatus used to execute the method was calibrated using NIST standard glass. FIG. 2 shows schematics of the apparatus.

The apparatus (1) for measuring melt viscosity comprised a platinum ball (2) with a diameter of 16 mm. The platinum ball (2) was hung on a thin platinum wire (6) with the help of a special bracket/holder (11) attached to the right scale of the analytical balance. Initially, the first the end of the platinum wire (6) was attached to the bracket/holder at point A. After warming the furnace (9), the platinum ball was placed in the sample melt inside the crucible (3) and the first end of the wire was attached to the bracket/holder at point B to locate the platinum ball (2) in the center of the melt. The distance between the platinum ball (2) and the walls of the crucible (3) was 13-15 mm. If the distance were smaller, it would affect the precision of the measurement.

The movement of the platinum ball (3) in the melt was performed by changing the weight of the rider. The speed of the movement of the ball in the melt was defined in relative numbers of the balance indicator shift that was observed on the balance scale. When the balance indicator moved 100 points to both sides from zero position, the ball in the melt shifted 1.7 mm from the central position up and down. The sensitivity of the balance was 10 mg per 100 points. A Pt/PtRh thermocouple was placed in the furnace next to the crucible (3) and provided automatic temperature control of the furnace. The hot end of another thermocouple (5) was inside the crucible (10) filled with Al₂O₃ powder. This thermocouple was connected with the potentiometer to control the furnace temperature at the set point. The temperature control had a precision ±1.5° C.

During the testing, the platinum ball (2) moved from a marked upper position in the melt to a lower marked position under its gravity, the time of which was recorded using a stopwatch with the precision within 0.1 second. The time of the balance scale shift to 20-60 scale divisions was measured depending on the viscosity of the melt. The speed of the platinum ball (2) movement (per scale division/seconds) was taken as an average value of six measurements.

Using the velocity (V)—weight (G) data, a plot of V-G was constructed for each glass composition under investigation, all of which showed straight lines passing through the point of origin of the V-G coordinates. The slope k of each line was correlated with melt viscosity in a form of: log η=a*log(tgk)+b where a (1.09) and b (0.87) were constants determined from cell calibration using a NIST standard glass (710A). The relative error in defining viscosity was within 3% over the viscosity range, 2.5<log η<3.5, and within 4-6% over the range, log η<2.5 and log η>3.5.

The measurement of glass composition liquidus temperature (T_(L)) was conducted in a tube type gradient furnace with maximum temperature 1250° C. The furnace chamber had a dimension of 480 mm in length and 50 mm in diameter. The geometry and dimension of the furnace were close to those recommended by the ASTM C829-81. FIG. 3 illustrates the position of the thermocouple and the number of turns of the heating coil. The coil was made of NiCr resistance alloy wires with diameter of 2 mm.

Table VIII summarizes measured liquidus temperature (T_(L)) and reference temperature of forming (T_(F)) defined by melt viscosity of 1000 Poise for glass compositions of Examples 1-22. Glass compositions of Examples 1-6 demonstrated liquidus temperatures greater than 1240° C., the upper limit of the gradient temperature furnace setting. As a result, no viscosity measurements were made for these compositions for a determination of forming temperature. Moreover, several glass compositions displayed desirable melt properties by having lower liquidus and forming temperatures while maintaining a difference in liquidus temperature and forming temperature of at least 65° C. Examples 18, 20 and 21 each provided a forming temperature under 1222° C. while maintaining a difference in liquidus and forming temperature of at least 75° C.

TABLE VIII Melt Properties of Glass Compositions T_(L) T_(F) Delta T (T_(F) − T_(L)) Example (° C.) (° C.) (° C.) 1 1235 1226 −9 2 >1240 3 >1240 4 >1240 5 >1240 6 >1240 7 1296 8 1190 1265 75 9 1290 10 1185 1246 61 11 1190 1236 46 12 1130 1265 135 13 1185 1224 39 14 1155 1248 93 15 1085 1250 165 16 1170 1225 55 17 1180 1204 24 18 1135 1222 87 19 1090 1252 162 20 1140 1220 80 21 1130 1205 75 22 1120 1262 142

Table IX summarizes measured liquidus temperature (T_(L)) and the forming (T_(F)) temperature for glass compositions of Examples 40 through 71 as a function of weight percent of Li₂O in the glass compositions. As provided in Table IX, Li₂O plays a significant role in lowering the liquidus and forming temperatures of glass compositions of the present invention with minimum reductions in forming and liquidus temperatures being 30° C. and 43° C. respectively.

TABLE IX Melt Properties of Glass Compositions High Li₂O (1.5 wt %) Low Li₂O (0.5 wt %) Delta Delta EX. T_(F) ° C. T_(L) ° C. T ° C. EX. T_(F) ° C. T_(L) ° C. T ° C. 42 1148 1060 88 40 1187 1100 87 44 1156 1054 102 41 1176 1073 103 45 1157 1065 92 43 1165 1083 82 47 1145 1058 87 46 1179 1081 98 51 1142 1067 82 48 1210 1096 114 52 1158 1054 104 49 1210 1098 112 55 1154 1031 123 50 1206 1086 120 56 1160 1024 136 53 1193 1084 109 58 1164 1062 102 54 1205 1090 115 59 1124 1054 70 57 1222 1074 148 61 1160 1054 106 60 1204 1087 117 62 1148 1043 105 63 1215 1068 147 65 1163 1065 98 64 1192 1073 119 66 1162 1057 105 67 1190 1073 117 69 1154 1060 94 68 1190 1087 103 70 1158 1060 98 71 1208 1073 135

FIG. 4 provides temperature-viscosity curves for the glass composition of Example 18, two E-glass compositions and a C-glass composition. From FIG. 4, it is noted that the temperature-viscosity characteristics of the glass composition of Example 18 are similar to those of the C-glass composition. Moreover, the viscosity change for the glass composition of Example 18 is not as steep as that provided for the E-glass compositions. As a result, the glass composition of claim 18 can be characterized as a “long” glass whereas the E-glass compositions are “short” glasses. Longer glasses, such as Example 18, in principle, favor fine filament production forming due to less forming tension as a result of slower reduction in melt viscosity over the forming temperature range right after fiber exit from the forming tip.

FIG. 5 further illustrates the reduction in forming tension by providing molten glass surface tensions as a function of temperature for the glass composition of Example 22 in comparison two E-glass compositions. As provided in FIG. 5, the glass composition of Example 22 at the forming temperature has 9% and 14% lower surface tension than the E-glass compositions.

FIG. 6 is a plot of the melt or molten glass density as a function of temperature for the glass composition of Example 22 in comparison with two E-glass compositions. As provided in FIG. 6, the glass composition of Example 22 demonstrated a temperature dependency (slope) similar to the E-glass compositions but had a molten density 5% and 7% lower than the E-glass compositions respectively. As a result, glass fibers formed from some glass compositions of the present invention are lighter per unit volume in comparison to some E-glass fibers. Lighter glass fibers can be advantageous in many applications, particularly material reinforcement application, such as polymeric reinforcement applications, where weight savings are highly desirable. Moreover, as a result of lower densities, glass fibers formed from some glass compositions of the present invention can have larger diameters in comparison to some E-glass fibers of the same weight, thereby providing enhanced mechanical properties.

FIG. 7 is a plot electrical of conductivity as a function of temperature for the glass composition of Example 25 in comparison with E-glass and C-glass compositions. As provided in FIG. 7, the glass composition of Example 25 and the C-glass composition display much higher electrical conductivities than the E-glass due to their significantly higher alkali metal content. The melt conductivity of an inorganic glass composition is generally dominated by the mobile ions of sodium and potassium. As a result of low sodium and potassium ion content in E-glass compositions, electrical melting technology is only used as a secondary boost system for E-glass processing. However, electrical melting technology has been used as a primary energy for the processing of C-glass compositions. Given that glass compositions of the present invention, in some embodiments, demonstrate higher melt conductivities than some C-glass compositions, electrical melting technology may find application to processing glass compositions of the present invention.

Additionally, glass compositions of the present invention formed from batch compositions comprising perlite and/or pumice, in some embodiments, require less energy for converting the batch composition to a glass melt composition. FIG. 8 provides the energy required to convert the batch composition comprising perlite to the glass melt composition of Example 12. FIG. 8 also provides the energy required to convert an E-glass batch composition to the associated glass melt. As shown in FIG. 8, the energy required to convert the batch composition of Example 12 into a glass melt composition was 20% less than the energy required to convert the E-glass batch composition to glass melt composition. The energy required to convert a second E-glass batch composition to a glass melt composition was also compared with the energy required to convert the batch composition of Example 12 into a glass melt composition. The energy required to convert the batch composition of Example 12 was about 33% percent lower than the energy to convert the second E-glass batch composition to a glass melt composition.

II. Acid and Alkaline Corrosion Resistance

Fibers formed from glass compositions of the present invention were made in a laboratory using a single tip bushing set up. To compare with commercial glass fiber corrosion resistance under the same testing conditions, AR-, C-, ECR- and E-glass fibers were also made using the same method using cullet.

Glass fiber resistance to corrosion was evaluated in terms of the relative sample percent weight loss after leaching test. Testing was administered by boiling a fiber strand at 100° C. for one hour in sulfuric acid or sodium hydroxide solutions under various pH conditions. All of the tests were performed by keeping ratio of solution volume to the sample mass or volume (5,000 m²) constant. 50 ml of the solution and of 1.375 gram (filament diameter—22 μm) were used for each test. Triplicate samples were tested to determine average sample weight losses. The results of the acid and alkaline corrosion resistance testing are provided in Table X.

TABLE X Acid and Alkaline Corrosion Resistance Results (% Weight Loss) 0 2 12 14 1N 0.1N 0.1N 1N pH H₂SO₄ H₂SO₄ NaOH NaOH Note E-glass (1) 1.02 0.19 0.29 1.24 0 B₂O₃ E-glass (2) 1.04 0.00 0.51 0.92 1.3 B₂O₃ E-glass (3) 17.79 0.87 1.62 6.0 B₂O₃ ECR 0.66 0.00 0.13 1.11 0 B₂O₃ + 4 ZnO C-Glass² 0.09 0.13 0.36 7.83 0 B₂O₃ AR-Glass 0.10 0.00 0.00 0.10 17 ZrO₂ I³ Ex 10 1.12 0.21 0.84 6.42 Baseline Ex 11 3.58 0.15 0.38 5.60 1% ZrO₂ + 3% TiO₂ Ex 12 4.38 0.21 0.62 2.23 2.9 ZrO₂ + Ex 13 4.79 0.64 0.40 1.01 1.1% TiO₂ 8% ZrO₂ Ex 12 0.59 0.22 0.26 8.13 baseline Ex 38 1.50 0.09 0.68 11.02 Ex 18 3.10 Ex 19 0.69 0.66 0.31 8.47 Ex 57 2.20 2.29 Ex 58 2.75 3.81 Ex 59 5.35 5.54 Ex 63 1.64 2.89 Ex 67 1.35 3.57 Ex 71 1.19 3.30 ¹ The average determined from three individual tests and standard deviation is not greater than 0.1%. ²C-glass (wt %): 66 SiO₂, 5.5 Al₂O₃, 10.4 CaO, 3.6 MgO, 0.3 Fe₂O₃, 0.2 K₂O, 12.5 Na₂O, 0.5F and 0.2 SO₃. ³AR-glass (wt %): 57 SiO₂, 3.2 Al₂O₃, 15 ZrO₂, 4.2 CaO, 0.1 MgO, 0.1 Fe₂O₃, 0.1 K₂O, 12 Na₂O, 0.5 F and 0.23 SO₃.

III. Mechanical Testing

Tensile strengths of fibers formed from the glass composition of Example 37 of the present invention were measured by drawing 10-um diameter fibers from single tip bushing in laboratory. The fibers were subsequently tested by applying tensile force to the fibers from both ends within the same day of fiber forming. FIG. 9 summarizes Weibull statistical analysis of the fiber strength with an average of about 3050 MPa and standard error of 22.4 MPa for sample size of 57. Except for the tail, the strength fit the single Weibull distribution well suggesting a single failure mode dominates the fiber failure.

Fiber sonic tensile modulus was measured by drawing 30-um diameter fibers comprising the glass composition of Example 37 of the present invention from a single tip bushing in laboratory. The fibers were subsequently tested by applying dead weight from both ends to measure velocity of sound traveling inside the fiber. Fiber density was also measured. The elastic modulus was calculated using E=pC² where E, p, and C are modulus, density, and sound velocity, respectively. Fibers of two sets were formed at two different temperatures, the first set at 1000 Poise melt viscosity (Low T Forming) and the second set at 50° C. higher than the first set. (High T Forming) Table XI summarizes the statistical analysis of the fiber modulus with an average of about 56.8 GPa and 61.5 GPa for low and high forming temperature cases, respectively.

TABLE XI Tensile Modulus Statistics Low T Forming High T Forming Mean (GPa) 56.79 61.47 Std Dev (GPa) 4.41 6.73 Std Err Mean (GPa) 0.99 1.37 upper 95% Mean 58.86 64.31 lower 95% Mean 54.73 58.62 Sample Size N 20 24 Fiber Diameter (μm) 29.96 ± 0.36 30.17 ± 0.42 Fiber Density (g/cm³)  2.356 ± 0.006  2.251 ± 0.028

Desirable characteristics, which can be exhibited by embodiments of the present invention, can include, but are not limited to, the provision of new glass compositions that utilize glassy minerals; the provision of new glass compositions that utilize perlite; the provision of batch compositions requiring less energy to form melts of glass compositions; the provision of new glass compositions demonstrating significant differences in liquidus and forming temperatures; the provision of glass fibers having reduced weights without a concomitant reduction in mechanical properties; and the provision of glass fibers demonstrating desirable acid and alkaline corrosion resistance properties.

It is to be understood that the present description illustrates aspects of the invention relevant to a clear understanding of the invention. Certain aspects of the invention that would be apparent to those of ordinary skill in the art and that, therefore, would not facilitate a better understanding of the invention have not been presented in order to simplify the present description. Although the present invention has been described in connection with certain embodiments, the present invention is not limited to the particular embodiments disclosed, but is intended to cover modifications that are within the spirit and scope of the invention, as defined by the appended claims. 

That which is claimed:
 1. A method of producing a glass fiber, the method comprising: (a) providing a batch composition comprising: at least 10 weight percent of a glassy mineral and at least 5 weight percent of a sodium source, the glassy mineral comprising a combination of SiO₂ and Al₂O₃ in an amount of at least 80 weight percent; at least 10 weight percent of an additional source of silicon, aluminum, or both silicon and aluminum; and a sufficient amount of an alkali metal oxide (R₂O) component comprising K₂O, such that the glass fiber produced comprises 8.5 to 18 weight percent of R₂O and further comprises from 0.5 to 4 weight percent K₂O; (b) heating the batch composition to form a molten glass composition; and (c) extruding the molten glass composition through a bushing to form a glass fiber.
 2. The method of claim 1, wherein the batch composition is heated to a fiber forming temperature ranging from about 1120° C. to about 1300° C.
 3. The method of claim 1, wherein the batch composition is heated to a temperature ranging from about 1400° C. to about 1450° C.
 4. The method of claim 1, wherein the batch composition is heated to a fiber forming temperature which differs from a liquidus temperature of a glass composition from about 45° C. to about 165° C.
 5. The method of claim 1, wherein the batch composition comprises at least 25 weight percent of the glassy mineral.
 6. The method of claim 1, wherein the batch composition comprises at least 40 weight percent of the glassy mineral.
 7. The method of claim 1, wherein the glassy mineral comprises perlite, pumice or mixtures thereof.
 8. The method of claim 1, wherein the batch composition comprises at least 10 weight percent of the sodium source.
 9. The method of claim 1, wherein the batch composition comprises at least 10 weight percent of an additional source of silicon.
 10. The method of claim 9, wherein the source of silicon comprises 34-56 weight percent silica.
 11. The method of claim 1, wherein the batch composition comprises at least 10 weight percent of an additional source of aluminum.
 12. The method of claim 11, wherein the source of aluminum comprises corundum.
 13. The method of claim 1, wherein the batch composition comprises at least 10 weight percent of an additional source of both silicon and aluminum.
 14. The method of claim 13, wherein the source of both silicon and aluminum comprises at least one of kaolinite, dickite, halloysite, nacrite, montmorillonite, or alkali metal aluminosilicates.
 15. The method of claim 14, wherein the source of both silicon and aluminum comprises up to 19 weight percent kaolinite.
 16. The method of claim 1, further comprising at least one additional mineral comprising limestone, dolomite, or mixtures thereof.
 17. The method of claim 16, wherein the additional mineral comprises up to 55 weight percent dolomite.
 18. The method of claim 16, wherein the additional mineral comprises up to 17 weight percent limestone.
 19. The method of claim 1, wherein the glass fiber comprises: 53-64 weight percent SiO₂; 8-12 weight percent Al₂O₃; and a metal oxide (RO) component comprising MgO, CaO, SrO, BaO, or ZnO or mixtures thereof, wherein the metal oxide component is present in an amount to provide a mass ratio of R₂O/RO ranging from about 0.28 to about 1.5. 